In a Long Term Evolution (LTE) system, in order to achieve uplink frequency-domain scheduling, in addition to send a demodulation reference signal on the data transmission frequency band of the User Equipment (UE) itself, the UE also needs to send a sounding reference signal SRS on a frequency band which has a bandwidth greater than that of the data transmission frequency band, so as to perform sounding on the channel, thereby realizing the purpose of assisting the base station to allocate the uplink transmission resource to the UE.
By utilizing the SRS and the channel reciprocity, it is easy to implement a series of complex multi-antenna technologies, such as SU-MIMO/Beamforming, MU-MIMO/Beamforming, SU-CoMP and MU-CoMP, in the LTE system, so that multiple transmitting antennas may be supported at the UE side. For example, in an LTE-A system, the UE can send the SRS by using multiple transmitting antennas (typically the number of the transmitting antennas is 2 or 4, etc.), and therefore the system is required to allocate more SRS Time Frequency Code (TFC) resource to transmit SRS. In addition, in the LTE-A system, the allocation of the uplink transmission resource for the UE supports a cluster-based allocation. According to the cluster-based allocation, the uplink resource may be allocated to sub-bands far away from each other. Therefore, in order to support the user scheduling and the uplink precoding, the UE needs to send an SRS on a wider frequency band to perform sounding on the channel. This will further increase the requirement for SRS time frequency code resource, which will in turn lead to the significant increase of the uplink overhead and reduce the efficiency of the uplink transmission spectrum.
In the prior art, the requirement for the time frequency code resource in certain time period for sending the SRS can be reduced in a manner of extending the period for sending the SRS. However, the extension of the sending period will bring the problem of lower precision of channel information estimation.